Power LED is a point source of light. A LED luminaire consists of a number of power LEDs connected in series or parallel or a combination of the two. The luminaires are designed to provide the right amount of light to the target area. The light level is adjusted by dimming to meet the user specific light requirement.
A typical luminaire provides light equally in all directions. The evenly distributed light is not completely utilized by the target area. For example, if a down light is mounted near a wall, as some amount of light falls on walls, not on the floor below the down light. In case of indoor application, light gets wasted by non-reflecting walls whereas in outdoor application lights get wasted in the surroundings. FIG. 1 shows an example of tunnel lighting: some light emitted from the luminaire falls to the wall and the ceiling, such as shown by the circular sectors on the wall and the ceiling. If the wall is far away from the target area, light gets wasted even if the wall is reflective. This light loss causes wastage of energy.